Return-Path: X-Spam-DCC: paranoid 1102; Body=2 Fuz1=2 Fuz2=2 X-Spam-Checker-Version: SpamAssassin 3.1.3 (2006-06-01) on lipkowski.org X-Spam-Level: X-Spam-Status: No, score=-2.0 required=5.0 tests=BAYES_00,DNS_FROM_AHBL_RHSBL, HTML_30_40,HTML_MESSAGE autolearn=no version=3.1.3 Received: from post.thorcom.com (post.thorcom.com [195.171.43.25]) by paranoid.lipkowski.org (8.13.7/8.13.7) with ESMTP id t95BWn6c010870 for ; Mon, 5 Oct 2015 13:32:49 +0200 Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1Zj3x9-0007Sd-N3 for rs_out_1@blacksheep.org; Mon, 05 Oct 2015 12:29:11 +0100 Received: from [195.171.43.32] (helo=relay1.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1Zj3x8-0007SU-Vz for rsgb_lf_group@blacksheep.org; Mon, 05 Oct 2015 12:29:10 +0100 Received: from mail-wi0-f176.google.com ([209.85.212.176]) by relay1.thorcom.net with esmtps (TLSv1.2:ECDHE-RSA-AES128-GCM-SHA256:128) (Exim 4.86) (envelope-from ) id 1Zj3vz-0006FO-CN for rsgb_lf_group@blacksheep.org; Mon, 05 Oct 2015 12:29:09 +0100 Received: by wicge5 with SMTP id ge5so115778756wic.0 for ; Mon, 05 Oct 2015 04:27:45 -0700 (PDT) X-DKIM-Result: Domain=gmail.com Result=Good and Known Domain DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=mime-version:in-reply-to:references:date:message-id:subject:from:to :content-type; bh=9E3WY5S/fnsIcIqX7hSPXerZyd/yA/KwlYc8uUU9Ja0=; b=1Hp4GBa0WmJIKIGAKKmjvYNFB/RQUGN7eIuU0mWduAIcaCiqWC40wYAYyv7ClC0XvI lX36FoXbkVNPJt/4RfiObmP4/5gHbLDU3v3Q3tHL0tSJt8UEeCW7Z66pyauSNJqmsJkK BLkpByvlpdYuGSR7KmMU94VjdYrgfX3fOVDkzb5lThEIBUgO1SC7qYZ3V6Wkxyv4ZhZn shVP0xMyEUUnayqGRE2hmvZLdU3Y11HRGrfmZ2p1972suxQzxQUbAX/BcEWDG4GIpQeD 0zN/jGcZ4Yh+ORr41XDhkLtGH/dQRB10RegwtLT+iairnVvAFPb7TtIDF8N4IVF9MlTF /9XQ== MIME-Version: 1.0 X-Received: by 10.194.90.47 with SMTP id bt15mr32885493wjb.18.1444044464875; Mon, 05 Oct 2015 04:27:44 -0700 (PDT) Received: by 10.28.47.212 with HTTP; Mon, 5 Oct 2015 04:27:44 -0700 (PDT) In-Reply-To: <0LmKOI-1aGjgI2N50-00ZuP1@mail.gmx.com> References: <560DF24D.3050309@abelian.org> <0LmKOI-1aGjgI2N50-00ZuP1@mail.gmx.com> Date: Mon, 5 Oct 2015 12:27:44 +0100 Message-ID: From: Andy Talbot To: rsgb_lf_group@blacksheep.org X-Scan-Signature: 4c0633a540d76adc241b9d3cede72a57 Subject: Re: LF: Coherent BPSK on LF using EbNaut Content-Type: multipart/alternative; boundary=047d7bfd00625e7183052159cd05 X-SA-Exim-Scanned: Yes Sender: owner-rsgb_lf_group@blacksheep.org Precedence: bulk Reply-To: rsgb_lf_group@blacksheep.org X-Listname: rsgb_lf_group X-SA-Exim-Rcpt-To: rs_out_1@blacksheep.org X-SA-Exim-Scanned: No; SAEximRunCond expanded to false X-Scanned-By: MIMEDefang 2.56 on 10.1.3.10 Status: O X-Status: X-Keywords: X-UID: 4268 --047d7bfd00625e7183052159cd05 Content-Type: text/plain; charset=UTF-8 Continuing on this theme... Having abandonned my idea of a direct conversion Rx due to uncontrollable DC offsets, and not yet finished a locked clock for my SDR-IQ, I wondered about the next stage. The idea is to overcome errors and drift in sound cards, and ideally make any coherent receiver non-dependent on the S/Card. So I was contemplating this solution as being worthy of further tests. Once the receiver (SDR-IQ here) is locked, its output can be delivered as an audio tone whose exact frequency is known. This adjusted to end up at exactly 1kHz and is applied to one input channel of a soundcard, Now, I can generate an exact 1kHz tone by dividing down from the same reference signal and send this to the other soundcard channel. So now, we have independant reference and test inputs to the Soundcard and it doesn't matter how unstable its own clock is; the phase of the input signal can always be compared with that of the reference input. In fact, my gut feeling is that the less stable the soundcard clock is, after a bit of averaging a better result will ensue. Thoughts ? The idea of making the soundcard's clock irrelevant appeals. And generating a nice reference 1kHz tone is dead easy. Andy G4JNT --047d7bfd00625e7183052159cd05 Content-Type: text/html; charset=UTF-8 Content-Transfer-Encoding: quoted-printable

Continuing on this theme...=
Having abandonned my idea of a direct conv= ersion Rx due to uncontrollable DC offsets, and not yet finished a locked c= lock for my SDR-IQ, I wondered about the next stage.

The idea is to overcome erro= rs and drift in sound cards, and ideally make any coherent receiver non-dep= endent on the S/Card.=C2=A0 So I was contemplating this solution as being w= orthy of further tests.=C2=A0 Once the receiver (SDR-IQ here) =C2=A0is lock= ed, =C2=A0its output can be delivered as an audio tone whose exact frequenc= y is known. =C2=A0 =C2=A0This adjusted to end up at exactly 1kHz and is app= lied to one input channel of a soundcard,=C2=A0

Now, I can generate an exact 1kHz= tone by dividing down from the same reference signal and send this to the = other soundcard channel. =C2=A0 So now, we have independant reference and t= est inputs to the Soundcard and it doesn't matter how unstable =C2=A0it= s own clock is; the phase of the input signal can always be compared with t= hat of the =C2=A0reference input.=C2=A0 In fact, my gut feeling is that the= less stable the soundcard clock is, after a bit of averaging a better resu= lt will ensue.=C2=A0

Thoughts ?

The idea of making the soundcard's clock irreleva= nt appeals. =C2=A0=C2=A0
And generating a n= ice reference 1kHz tone is dead easy.

<= /div>
Andy =C2=A0G4JNT




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